Blow-off tank for steam boilers



May 14, 1935.

P. M. GREEN LAW BLOW-OFF TANK FOR STEAM BOILERS FiledApril 13, 1954 F-II I 54W PRICE M. GREEN LAW,

Patented May 14, 1935 UNITE STATES PATENT OFFICE 2,001,249 r V t BLOW-OFF TANK FOR STEAM BOILERS Price M. Grcenlaw, Washington,.D. 0. Application April 13, 1934, Serial No. 720,465

3 Claims. (Cl..122-379) This invention relates to clean-out devices or cheapness of manufacture and installation, its systems for-steam boilers and particularlyto a durability and highly efficient action in use. device commonlyrecognized as a blow-oft tank. Other important objects and advantages of It is well recognized in the art that steam boilthe invention will present themselves during the 5 ers accumulate considerable sediment over the course of the following descriptiomreference be- 5 inner surfaces, caused to be deposited thereon by ing had to the accompanying drawingin which, chemical changes in the water and unless this Figure 1 is a longitudinal section through a dedepos'it is removed at frequent intervals, serious vice constructed in accordance with the inven damage with its attendant danger will result. tion and,

l0 7 Many attempts have been made to provide sat- Figure 2 is a. transverse section on line 2-2 10 isfactory means for permitting afrequent blow- 'of Figure ,1. off or clean out of the boiler, necessitating high- Like numerals refer to like parts throughout. 1y expensive equipment, as a result of many mu- In the drawing, the numeral 5 designates a nicipal regulations, since theblow-ol'f cannot be metallic tank, preferably of cylindrical form.

1.5 directed to the atmosphere nor directly to a The tank 5 is formed of suitable'heavy gauge r, 7 sheet metal, having ends 6 and l, welded or oth- It is a purpose of the present invention to proerwise secured thereto. A man-hole 8 is provided vide a tank so arranged as to permit the blowin the end 6 to permit accessto the interior of off pipe from the boiler to discharge directly thetank. The tank is preferably'supported in 2Q therein with a minimum of noise and the com- ,spaced relation to the floor as indicated at 9.

plete absenceof objectionable vapors. Leading into the tank 5 preferably centrally A further object resides in the, provision of a thereof, is a blow-01f pipe ID from, the boiler, not device so constructed as to receive the discharge shown; and having a cut-off valve I l. Leading from the boiler blow-01f and to conduct such from the tank at the opposite end I, is an overblow-off products therethrough in such manner flow pipe l2; The pipe I2 is of a size approxi- 25 as to permit their final discharge directly to a mately four times the diameter of the pipe Ill, sewer, drip pan or the like. and as clearly shown has its inner end 83 turned In prior devices, great difficulty and expense downward and terminating in spaced relation to has been encountered in finding a suitable and the bottom of the tank. The outer or free end 439 lawful discharge for the steam vapors from the i4 may be directed to a convenient sewer conblow-off and in many cases, especially in crowdnection or into a suitable drip receptacle. ed communities, it has been necessary to pro- Means areprovided to remove anyaccumulated vide a pipe line from the. blow-ofi tank to the "sediment from around the inlet end l3 of the roof of the structure, often requiring many pipe l2, comprising a blow-off pipe [5 having .85 bends and joints inthe linef In such cases it communication, with the interior of the tank has been found that the joints orbends of the through an opening l6, that is concentric with line have gradually become clogged'rup with an the open end IS. A cut-off valve l'l controls the accumulation carried upward by the escaping discharge through the pipe Hi. The pipe I5has steam, and when this condition exists, great danconnection with the discharge end M of pipe I2 .40 ger of explosion is present in the blow-01f tank, as Shown t m, t h m be noted t t i t 40 the steam, of such length as may amply 'be since these tanksare not ordinarily constructed ystem of discharge t r are no abrupt joints or 9 wlthstand holler P e avolfi} 11118 other points that might tend to accumulate sedih 1ghly dangerous COl'ldIlZIOII, thepresent invenment As clearly shown the pipe '2 passes tlon aims to provide means forming a vent for through a t bl coupling in the end 1 and the 7 position of the pipe is such as to maintain a level 522E22 g g s g ggi gggj 13g 322 2: :3 of water in'the tank on a line approximately with may enter the vent, returning the products of the Inner end of the plpe V condensation back to the tank Arranged near the end Band pro ecting in a I A further object of the invention resides in Yertlcafl posmon 1s co'mbmed Vent and 50 the extreme simplicity of the device, embodying densatwn stack Thls Stack has m unusual fe ture of afety as will permit the cation with the interior of the tank through an installation of the device in municipalities havopening 28 a d ha i s upp end f med enti e y ing strict regulations; open, with theexception of a supporting spider Anotherand important objectis the extreme 2|, adapted to receive and centrally position a 55 water supply pipe 22 having a spray head 23 although it should be understood that there is no restriction on size. The stack is of a height such as'm'ay conveniently terminate within the boiler room; thus avoiding the necessity of conducting it to the exterior of the building.

A baflle plate 25 having reinforcing angle irons 28, is arranged within the tank about in a position intermediate the ends 6 and 'l.' 'The plate 25 is arranged at an angle of approximately 20 degrees from the vertical. As shown clearly in Figure 2, the upper portion of the plate 25is shaped to conform to the curvature of the tank; and completely separates the upper half of the tank into separate air chambers. The lower or straight edge of the plate terminates, a few inches below the normal surface of the water, leaving a relatively large. passage therebelow for the pas- V sage of the water'tofthe drain. Primarily, the

object of this 'plate'25 is to provide a means for retarding the velocity of the incoming water and steam from pipe i0, and this is accomplished by the fact that as the steam and water enter from pipe is, they engage the surface of the tank water, causing it to roll and dash against the baiiie; This action not only retards the velocity of the water, but reduces to a minimum the noise that would naturally be present, but for this arrangement. A vent pipe 21 leads from the, interior of the stack 8 to the top portion of thepipe 12in order to avoid the possibility of the pipe 12 serving as a siphon. j

The operation of the device is as followsz The device having been setup and filledito the normal level of the overflow with water from the pipe 22, the system is now'in condition for operation.

- Valves island 26 are now cpened which action permits the entry into the tank5 of boiling water and steam from the boiler' blow-off I0, carrying with it any accumulated scale or other sediment that has settled therein. The opening 'ofthe valve 24 permits the entry of pure water from them'ain supply which enters the stack l9 as a spray .from the head 23. Since the pipe I enters the tank at normal water level, the incoming water and steam from the boiler willengage the surface of the tank water causing it to roll and dash against the baflle plate 25. This action materially reduces or retards the velocity of the incoming water and steam and its engagement with the baffle plate throws the waterin a reverse direction. This reverse movement not only aids in reducing velocity, but further serves to reduce to a minimum the natural rumbling or churning sound usually present other devices. During this rolling or' dashing of the water, much moisture in vapor form is created with a consequent release of its heat content, and

such vapor together: with theincoming. steam tends to escape through the stack I9, where its passage upward is intercepted by the spray 23.

The spray thus condenses such vapor and the resultant water drops back to'the tank 5. The spray thus has a dual purpose, namely, to condensethe escaping vapors and to furnish a pure water supply for the'tank that will counteract the pittingaction of. the boiler water, thereby greatly prolonging the life of the tank.

During the blow-off period of the boiler, the tank will rapidly fill with water to a point near its top. Upon the closing of the valve 24 and valve H the tank will automatically drain to its normal water level through the overflow pipe l2, carrying with it the major portion of the deposited scale or sediment from the boiler. Since the end I3 is downturned as indicated, the discharge of the water will occur at a single point. Such action will naturally create a slight deposit at this point much in the shape of a doughnut around the inlet to the end l3, and it becomes necessary from time to time to remove this accumulation. To accomplish this the valve i1 is openedand the water normally remaining in the tank will'carry such sediment accumulation through the pipe l5. It becomes necessary from "time to time'toclean the entire inner surface of the tank and this may be accomplished by a removal of theman-hole cover 8. I The baffle 25 1s alsoacces'sible through the man-hole and from this point may be repaired or renewed.

It will be obvious from the'foregoing that an extremely simple and eificient form of mechanism hasbeen constructed to accomplish a purpose thathasheretoforeproven expensive and disagreeable as' to noise of operation. The structure may be set up adjacent a steam boiler with the vent stack'of such length as to terminate'within the boiler room, thus'avoidin'g the expense orcarrying the vapor'discharge to the roof of the building; The discharged or overflow water emerges from the tank free from steam or vapor and is of low heat content and in'this condition it is-per- 'missible to direct it into a convenientsewer trap or receptacle. The device is safe to a high degree, presenting little or no possibility 'of danger to the operator or system. Should the operator fail directed to the fact by the issuance from the stack l9 of steam and vapor. It'may be found desirable in some cases to position water circulating coils in the lower part of the tank 5 sea means of aiding in the heating ofyfeed water for the boiler and a further reductionin the heat content of the tank water. 7

It is to be understoodthat the'invention is not limitedto the precise arrangement shown, but that it includes within 1 its purview whatever changes fairly come within the terms or spirit ofthe appended claims. n

Having described my invention, what I claim is:

1. A blow-off device forsteamboilers comprising an elongatedcylindrical casing having closed ends, a blow-offpipe from a steam boiler leading into one end, an overflow pipe leading into the casing from the opposite end and havin a downturned end, a vent stack for the casing adapted to vent the steam vapors from the blow-off water discharged'intoi the cylindrical casing, vapor condensing means arranged in said stack. vent means for the said overflow pipe'exteriorly of the casin Qa baffle plate in said casing arranged in the path of travel of the incoming blow-off products and drain means for the casing.

2. A device ofthe character describedccmprising a cylindrical metallictank having closed ends, a blow-on" pipe leading into the tank at one end and a water level and overflow pipe leading into the opposite end, said overflow pipehaving an inner downturned end slightly 'spaced'from the bottom of the tank; vent means for the overflow pipe exteriorly of the tank, a vent stack for said tank open at its upper end, a spray device positioned in said stack centrally thereof, a baffie plate positioned in said tank intermediate its ends and a sediment drain device for the tank positioned adjacent the downturned end of said overflow pipe.

3. A structure of the character described comprising an elongated cylindrical tank having closed ends, a pipe leading into one end of the tank and having connection with the blow-oil coupling of a boiler, a valve for controlling the flow through said pipe, a water level and overflow pipe leading into the tank from the opposite end and having its inner end curved downward and terminating in spaced relation to the bottom of the tank, a vent stack of relatively large diameter having an open upper end and communicating with the interior of the tank, a water pipe leading into the upper end of the stack and held in a centralized position, a spray head carried by said water pipe and likewise positioned in said stack, a vent for said overflow pipe, a sediment drain pipe for the tank communicating with the interior of the tank through an opening concentric with the downturned end of the overflow pipe, a bafile plate arranged in said tank intermediate its ends and. positioned at an angle from the vertical, the lower edge of said baffle spaced from the bottom of the tank and a man-hole opening formed in one end of the tank.

PRICE M. GREENLAW. 

